Magnetic control systems



J y 1961 J. A. RAJCHMAN ET AL 2,994,069

MAGNETIC CONTROL SYSTEMS Original Filed Sept. 15, 1954 6 SheetsSheet 1INVENTORS JAN A.-RAJIZHMAN [51 BY ARTHUR W. Lu

ATTORNEY July 25, 1961 J. A. RAJCHMAN ETAL MAGNETIC CONTROL SYSTEMS 6Sheets-Sheet 2 Original Filed Sept. 13, 1954 I INVENTORS JAN A. Rum-1mmEl ARTHUR W. LEI

ll TTOR NE Y July 25, 1961 J. A. RAJCHMAN ETAL 2,994,069

MAGNETIC CONTROL SYSTEMS Original Filed Sept. 15, 1954 '6 Sheets-Sheet 3I 105 AM V 104 10a" 1 J I? .55 5h 3 5A QM ms t7 INVENTORS JAN A. RmcummBY Arm-ma W. LB

iTTURNI-Y July 25, 1961 J. A. RAJCHMAN EFAL 2,994,069

MAGNETIC CONTROL SYSTEMS Original Filed Sept. 15, 1954 6 Sheets-Sheet 4ifia'zgz-a' 117 .56. 1? d j j 1:"; a;

41 J Z J INVENTORS A I T JAN A. Rum-mm r5 7163 ARTHUR w. Lu

2; ATTORNEY y 1961 J. A. RAJCHMAN ETAL 2,994,069

MAGNETIC CONTROL SYSTEMS 6 Sheets-Sheet 5 Original Filed Sept. 13, 1954INVENTORJ U1 JAN A. RAJLHMANIS ARTHUR IN. LEI I? .62?

ATTOR NE) July 25, 1961 J. A. RAJCHMAN ETAL MAGNETIC CONTROL SYSTEMSOriginal Filed Sept. 15, 1954 6 Sheets-Sheet 6 OUT PUT INVENTORS JAM A.RAJEHMAN Er ARTHUR W. L1:

ITTORNEY United States Patent Original application Sept. 13, 1954, Ser.No. 455,725. Divided and, this application Nov. 30, 1956, Ser. No.

12 Claims, (Cl. 340-174) This invention relates to magnetic systems andparticularly to methods of and means for controlling electrical signalsby means for such systems.

This application is a division of our copending application entitledMagnetic Systems, Serial No. 455,725, filed September 13, 1954-, andassigned to the same assignee as the present invention.

Use is made in the electrical arts of magnetic material whose magneticproperties are characterized by substantially rectangular hysteresisloops. A hysteresis loop for a magnetic material in a cycliclymagnetized condition (that is, in cycles of equal amplitude and oppositepolarity magnetizing forces), is a curve showing, for each value ofmagnetizing force, two values of the magnetic induction, one when themagnetizing force is increasing, the other when it is decreasing. Arectangular hysteresis loop is one which is substantially rectangular inshape. it is assumed, as usual, that the curve is plotted in rectangularcoordinates with the magnetic flux plotted along the vertical axis andthe magnetizing force plotted along the horizontal axis. Ordinarily, theflux 4: and the (flux density per unit volume B are proportional.Material with rectangular hysteresis loops is useful in its qualities ofremembering its previous magnetization by a magnetizing force.

In a given infinitwimal volume of magnetic material, it is convenient toconsider the absolute value of the vector of magnetic induction (whichis the flux density at a point) in the absence of a magnetizing force asdefining the state of remanence of that volume. The state of remanencein that volume depends upon the magnetic properties of the material andthe previous histories of excitation, and is defined by a point ofintersection of the hysteresis loop and the magnetic induction (B) axis.

The intersections of the upper and lower horizontal portionsrespectively of a rectangular hysteresis loop with the vertical (flux)axis, represent two states of saturation at remanence. One loop, calledthe major loop, is that approached as a limiting curve by increasinglylarge values of magnetizing force.

There is a family of minor loops each similar to the major loop on asmaller scale and each reflecting the shape of the major loop. Eachminor loop has its own two intersections with the flux axis, oneintersection representing a given state of saturation at remanence, andthe other intersection representing the opposite state of saturation atremanence.

Among the materials exhibiting the desired rectangular hysteresis loopsare certain ferro-magnetic spinel materials such as manganese-magnesium,and certain metallic materials such as mopermalloy.

There are two senses of flux flow around a closed path. A positivecurrent flowing into a surface bounded by the path produces a clockwiseflux flow in the path. One state of saturation at remanence, withreference to a closed flux path, is that in which the saturating flux isdirected in a clockwise sense (as viewed from one side of the surface)around the closed path; and the other state of saturation at remanenceis that in which the saturating flux is directed in the counterclockwisesense (as viewed from the same side of the surface) around the closedpath. The convention is adopted that the upper 2,994,069 Patented July25, 1961 horizontal loop intersection with the vertical flux axis is theP (positive) state of saturation at remanence and corresponds to the onestate with reference to the closed flux path; and that the lowerhorizontal loop intersection with the vertical flux axis is the N(negative) state of saturation at remanence and corresponds to the otherstate with reference to the closed flux path.

Examples of the use of the rectangular hysteresis loop magnetic materialmay be found in magnetic amplifiers, and in electrical computers havingregisters and memories that use magnetic cores. In magnetic amplifierdevices, the operation depends on the combined effect on the magneticmaterial of a simultaneous energizing source and a controlling signal.The magnetic core registers and memories utilize the magnetic materialof the cores as a static storage device. By means of the presentinvention, rectangular hysteresis loop magnetic material is employed toobtain advantages found in both magnetic amplifiers and magnetic coredevices.

It is an object of this invention to provide an improved magnetic systemby means of which electric signals representing, for example, asintelligence, power, etc., can be controlled in accordance with thesetting of an electric impulse.

Another object of this invention is to provide an improved magneticsystem and method of operation thereof for controlling electric signalsin such a manner that no holding power is required in the exercise ofthe control.

Still another object of this invention is to provide an improvedmagnetic system and method of operation thereof for storing information.

Still another object of this invention is to provide an improved methodof and means for storing information.

Yet another object of the present invention is to provide an improvedmagnetic storage device capable of retaining stored informationindefinitely notwithstanding repreated read-out.

A further object of the present invention is to provide a novel magneticstorage device having independent write and read circuits.

A still further object of the present invention is to provide animproved magnetic device of the character set forth above which isinexpensive to fabricate.

According to the invention, magnetic material saturated at remanence isused. The magnetic material has a plurality of distinct, closed fluxpaths. A selected one of the flux paths has two different portions ofmagnetic material saturated at remanence. Excitation means are providedselectively to excite the two different portions of a selected fluxpath, either to the same state of saturation at remanence along theselected path, or to opposite states of saturation at remanence alongthe selected path. An alternating magnetizing current is employed toapply alternating magnetizing forces along the selected path. Bysuitable means, for example an output winding linking the selected path,a response may be derived which is dependent on whether the selectedpath portions are in the same or opposite states of remanence withrespect to the selected path. Thus, the transmission of an alternatingcurrent signal may be controlled by the selection of the remanent statesof saturation of the selected path portions.

A device constructed according to the principles of the invention istermed a transfluxor. A transfluxor is made by providing two or moreapertures in a magnetic material having the characteristic of beingsubstantially saturated at remanence. These apertures are sufiicient toprovide at least three flux paths. A selected one of these flux pathshas portions common to at least two other flux paths. An appropriatemagnetizing force does or does not produce a substantial flux changealong the selected path depending upon whether it is magnetized alongits entire length in the same sense of saturation, or has portions in itsaturated at remanence in different senses. I

At any instant, an alternating input current (except when at zero value)which links a selected flux path causes a magnetizing force in one sensewhich tends to produce more flux in this one sense around the path. Ifall portions of the selected path are saturated at remanence in a commonsense along this path, an alter-' nating input current of givenamplitude (at least after the first half cycle) which links the pathreverses the flux sense repeatedly in this path. In such case, an outputvoltage is induced in an output winding linking the path as a result ofthe changing flux due to these reversals. If, now, any two of theseportions are saturated at remanence in opposite senses along the path,the instantaneous magnetizing force tends further to saturate one of thetwo specified portions in the sense in which it is already saturated.Because of the saturation, however, further appreciable flux change ofthis one portion cannot occur in this one sense. Therefore, there issubstantially no flux change in the selected path and substan tially novoltage is induced in the output winding.

Several embodiments of a transfiuxor are described hereinafter. In someembodiments the transfluxor may have only two apertures for each unit.Others may have three or more apertures. The output may be taken by wayof a single winding or by way of two windings. The transfluxor may bearranged to produce an output on one winding for one polarity of inputsignal, and a signal on another output winding for a difierent polarityof input signal.

The invention will be more fully understood, both as to its organizationand method of operation, from the following description when read inconnection with the accompanying drawing in which: a

FIG. 1a is a three-dimensional view of a transfluxor according to thisinvention, having three apertures, and showing a portion of its coupledinput and output windings;

FIG. lb is a schematic diagram of a magnetic system employing thetransfluxor of FIG. 1a;

FIGS. lc and 1d are composite rectangular hysteresis loops relating tothe transfluxor of FIG. 1a illustrating flux changes at a saturatedcondition;

FIGS. 2a, 2b, and 2c are three-dimensional views of irregularly-shapedbodies illustrating various conditions of flux flow therein, and usefulin considering the theory of operation of a transfluxor according tothis invention;

FIG. 3a is an idealized rectangular hysteresis loop, such as would bemost desirable for a material of the type used in practicing thisinvention;

FIGS. 3b and 3c are diagrammatic views of a simple magnetic circuithaving a single aperture, and also useful in considering the theory ofoperation of our transfluxor;

FIGS. 4a, 4b and 4c are diagrammatic views illustrating differentmethods by which an output winding may link a transfluxor of thisinvention;

FIG. 5a is a schematic view of another embodiment of a magnetic systememploying a transfluxor according to this invention and having twoapertures;

FIG. 5b is an end view of the transfluxor of FIG. 5a;

FIGS. 50, 5d and 5e are graphs of typical hysteresis loops relating tothe transfluxor of the two-aperture type shown in FIG. 5a;

FIG. 5f is a schematic diagram showing a modified form of thetransfluxor of FIG. 5a;

FIG. 6a isa schematic diagram illustrating a different mode of'operatinga magnetic system employing the transfluxor of FIG. 5a;

FIGS. 6b, 6c and 6d show various hysteresis curves relating to thestates of saturation of portions of the transfluxor of FIG. 6a; FIGS. 6eand 6 show representative waveshapes of 4 current pulses which may beapplied to the input windings of the transfiuxor of FIG. 6a;

FIG. 7 is a schematic view of a complete operating system including atransfluxor having two apertures according to this invention;

FIG. 8a is a schematic view of another system according to thisinvention, using a polarity-sensitive transfiuxor having five apertures;

FIG. 8b is an end view of the transfluxor of FIG. 8a, and

FIG. 8c is a schematic view illustrating a modified form of the systemof FIG. 8a.

Referring to FIG. 1a, there is shown a magnetic body 31 comprised of arectangularly-shaped plate of uniform thickness t. The plate 31 isprovided with at least three apertures 32, 34 and 36, each of which maybe of a diameter d. The three apertures may be located at acenter-to-center spacing C. The diameter d and the center-to-centerspacing C are chosen such that the widths of the legs 1, 2, 3 and 4along a longitudinal line through the centers of the apertures 32, 34and 36 are substantially equal. The diameters d may be unequal, and thespacings C may be unequal.

The plate 31 may, for example, be molded from a powder-like,manganese-magnesium ferrite and annealed at a suitably high temperatureto obtain the desired magnetic characteristics. Other rectangularhysteresis loop magnetic materials, such as mopermalloy, may beemployed.

The magnetic material limiting aperture 32 is linked by a winding 33,the magnetic material limiting aperture 34 is linked by a winding 35 anda winding 39, and the magnetic material limiting aperture 36 is linkedby a winding 37. The windings are shown as single-turn windings, butmulti-turn windings may be used, if desired.

In FIG. 1b, the winding 33 is shown connected to the fixed pair ofterminals of a reversing switch 112. The arms of the reversing switch112 are connected across a current source, such as a battery and aseries resistance 121. A switch 111 is interposed in one of the leadswhich connect the battery 110 and the reversing switch 112. The winding35 is connected to an AC. (alternating current) source 113. The winding39 is connected to a load 114. The winding 37 is connected across thefixed terminals of a reversing switch 117'. The arms of the reversingswitch 117 are connected across a current source, such as a battery 115and a series resistance 123. A switch 116 is interposed in one of theleads connecting the battery 115 and the reversing switch 117. Thearrows a, a, b, b, c, 0', adjacent the respective windings 33, 35, and37 indicate the conventional current flow in a direction opposite to theelectron flow. The operation of the magnetic system of FIG. 1b is asfollows: The reversing switch 117 is operated by throwing the movablearm tothe left (as viewed in the drawing) to connect the lead 37a of thewinding 37 through the switch 116 to the positive terminal of thebattery 115, and the lead 37b to the negative terminal of the battery11S. Upon closure of switch 116, a positive excitation current flows inthe winding 37 in the direction of arrow c, thereby causing a clockwiseflux flow around aperture 36. The clockwise flux flow around aperture 36is indicated by the solid arrows on the legs 3 and 4. The reversinvswitch 1'12 is operated by throwing the movable am up (as viewed in thedrawing) to connect the lead 33a of the winding 33 through the switch111 to the positive terminal of the battery 110, and the lead 33b to thenegative terminal of the battery 110. Upon closure of the switch 111, apositive excitation current flows in the winding 33 in the direction ofarrow a, thereby causing a clockwise flux flow around aperture 32. Theclockwise flux flow around aperture 32 is indicated by the dotted arrowson the legs 1 and 2. The'switches 116 and 111 may be closedsimultaneously or successively in any order. If the switches 1 16 and111 are then opened, the portions of the magnetic materialrespectivelylimiting the apertures 32 and 36 are in the one state, forexample, the state P, of saturation at remanence with reference torespective flux paths immediately around the apertures 32 and 36.

In many cases concerning multi-aperture magnetic circuits, it isconvenient to consider the direction of flux flow through a surfacewhich intersects some or all of the apertures, such, for example, as theplane represented by the dash line d--d of FIG. 2a. Thus, the directionof flux flow at any point of the surface is defined as along a normal tothe surface from one side A of the surface to the other side B of thesurface, or vice versa. One of these. two directions is selected as thepositive direction and the other of the two directions is then thenegative direction. In the example given and also hereinafter, theintersecting surface is chosen to. be a horizontal plane cutting theapertures. The horizontal plane is represented in FIG. 2b by the lineg-g'. The positive direction of flux flow in FIG. 2b is taken as beingin an upward direction, and the negative direction is taken as downward.In the case of the plane g-g', the direction of flux flow at any pointof the plane is always in the vertical, as illustrated.

Note that the sense of flux flow, and the corresponding state P or N ofsaturation at remanence, is taken with, reference to a closed flux path.The direction of flux flow in the respective legs 1, 2, 3 and 4 is takenas positive or negative without reference to a closed flux path, butwith reference to the intersecting surface, mentioned above.

In FIG. 1b, the vertical arrows applied to the respective legs 1, 2, 3and 4 indicate both the sense and the direction of flux flow around theapertures 32, 34 and 36. The dotted arrows on the legs 1 and 2 and thesolid arrows on the legs 3 and 4 indicate the sense and direction offlux flow in these legs subsequent to the application of a positiveexcitation current a and c to the windings 33 and 37. The legs 1 and 2which limit aperture 32, are both at state P of saturation at remanencewith reference to the flux path around aperture 32; and the legs 3 and 4which limit the aperture 36, are also both at state P of saturation atremanence with reference to the flux path around aperture 36. However,the legs 2 and 3, which limit the aperture 34, are at state N ofsaturation at remanence with reference to the flux path around aperture34. That is, the sense of flux flow around apertrue 34 iscounterclockwise. The direction of flux flow in the legs 1 and 3 ispositive, and the direction of flux flow in the legs 2 and 4 isnegative.

If, now, a positive excitation current is applied by the AC. source 113(FIG. 1b) to winding 35 in the direction of arrow b, a clockwise fluxflow is produced around aperture 34. When the positive excitationcurrent applied to the winding 35 is terminated, the state N ofsaturation at remanence of legs 2 and 3 is then reversed to a state P ofsaturation at remanence with reference to aperture 34. The flux flowaround aperture 34 induces a voltage of one polarity in output winding39 which links a portion of the magnetic material limiting the aperture34. The voltage induced in winding 39 is applied across the load device114. The direction of fi-ux flow in leg 2 is reversed to the positivedirection and the direction of flux flow in the leg 3 is reversed to thenegative direction.

Of the positive excitation current applied to winding 35 is followed bya negative excitation current, furnished by AC. source 113, in thedirection of arrow b a counterclockwise flux flow is established aroundaperture 34. The states of saturation at remanence of the portions ofthe magnetic material limiting the aperture 34, after the negativeexcitation current is applied, are reversed hack to the initial state Nof saturation at remanence. The directions of flux flow in the legs 2and 3, are also 6 reversed back to the respective negative and positivedirections, as shown by the. dotted arrows applied to the leg 2 and thesolid arrowapplied to the leg 3.

The sequence of alternate positive and negative excitationcurrentsapplied to winding 35 may be continued indefinitely. The stateof saturation at remanence of the portions of the magnetic materiallimiting the aperture 34, and the; directions of flux flow in legs 2 and3 reverse back and forth with the clockwise and counterclockwise fluxflow established by the corresponding excitation currents. A voltage isinduced in the output winding 39 each time the sense of flux flow in thepath around aperture 34 reverses.

Now, let the reversing switch 112 be operated by throwing the movablecontacts down to connect lead 33b through the switch 111 to the positiveterminal of battery and lead 33a to the negative terminal of battery110. Upon the closure of switch 111, a negative excitation current inthe direction of arrow a flows in winding 33, and a counterclockwiseflow of flux is established around aperture 32. When the switch 111 isopened, the state of saturation at remanence of the portions of themagnetic material limiting aperture 32 are reversed from the state P ofsaturation at remanence to the state N of saturation at remanence withreference to aperture 32. The sense of flux flow around the apertures32, 34 and 36, and the direction of flux flow in the legs 1, 2, 3 and 4'after the switch 111 is operated, are shown by the solid arrows appliedto the respective legs. The legs 1 and 2 are respectively reversed tostate N of saturation at remanence with reference to aperture 32.However, the leg 2 is at a state P of saturation at remanence and theleg 3 is at a state N of saturation at remanence with reference toaperture 34. The direction of flux flow in the legs 1 and 4 is negativeand the direction of flux flow in the legs 2 and 3 is positive.

If, now, a positive excitation current is applied by AC. source 113 tothe winding 35 in the direction of arrow b, no flux flow is producedaround the aperture 34 because the leg 2 is saturated and the fluxcannot be increased. Likewise, if a negative excitation current pulse isapplied by AC. source 113. to the winding 35 in the direction of arrowb, no flux flow is produced because leg 3 is saturated. Because nochange of flux flow occurs around the aperture 34, no voltage is inducedin output winding 39. Consequently, the response of the magnetic systemof FIG. 1b to a signal applied to winding 35 can be controlled by thepolarity of the excitation current previously applied to winding 33.

The postive excitation current applied to winding 37 is in the nature ofa reference excitation current for causing the portions of the magneticmaterial limiting aperture 36 to assume a reference state P ofsaturation at remanence, this being the state P in the example justdescribed. The opposite response to the excitation currents furnished bysource 113 is obtained when the opposite reference state N of saturationat remanence is established in the portions of magnetic materiallimiting aperture 36.

Now, assume that the portions of the magnetic material limiting aperture36 are at state N of saturation at remanence as a result of a referenceexcitation current in the direction 0' applied by the source 115.Assume, also, that the portions of the magnetic material limitingaperture 32 are at state P of saturation at remanence as a result of apositive excitation current in the direction of arrow 0. Under theseconditions, a flux flow is not produced around aperture 34 in responseto either the positive or negative excitation currents furnished bysource 113 because legs 2 and 3 are at opposite states of saturationwith reference to aperture 34. The flux flow is saturated and does notincrease in one of the legs 2 and 3 regardless of the sense of themagnetizing force resulting from current from the source 113. Suppose,however, that the portions, of the magnetic material limiting aperture32 are at state N of saturation at remanence instead of state P. In suchcase, as a result of a negative excitation current in the direction ofthe arrow a, flux flow is produced around aperture 34 as a result of thenegative excitation current in the direction b furnished by the source113. The subsequent positive excitation current in the direction bfurnished by source 113 then reverses the sense of flux flow aroundaperture 34 to the clockwise sense. The sequence of a negativeexcitation current followed by a positive excitation current reversesthe states of saturation at remanence of the portions of the magneticmaterial limiting aperture 34 back and forth between the states P and N.A voltage is induced in output winding 39 each time the sense of fluxflow in the path around aperture 34 is reversed.

Therefore, for a given state of saturation at remanence of the portionsof magnetic material limiting aperture 36, there is one setting of thestate of the magnetic material limiting aperture 32 in which the AC.signals furnished by source 113 are transmitted to output winding 39.Conversely, there is another setting of the state of the portions ofmagnetic material limiting aperture 32 in which the AC. signalsfurnished by source 113 are blocked from being transmitted to outputwinding 39.

The theory which follows is proposed as a plausible explanation of theexperimentally determined facts with which this theory is consistent.However, it is to be understood that the invention is not necessarilylimited by the theory presented herein.

One of the attributes of a magnetic circuit, as expressed inmathematical language, is that the divergence of magnetic induction iszero. Consequently, magnetic flux paths are continuous and close uponthemselves; and the quantity of magnetic flux flowing in a given path isthe same even though the area traversed by the flux path may bedifferent in different parts of the path.

For example, consider, as in FIG. 2a, an irregularlyshaped body ofmagnetic material such as the plate 100 having two apertures 101 and102. The plate 100 also may be of irregular thickness. The apertures 101and 102 divide the plate 100 into three different portions of magneticmaterial along the line dd. The apertures 101 and 102 also may be ofirregular shape. Each one of the three portions has a different widthmeasured along the line d-d'. Because the flux paths are continuous, theflux which flows in the portion of magnetic material on the left side ofaperture 101 (as viewed in the drawing) is equal to the flux which flowsin the portions of the magnetic material on the right side (as viewed inthe drawing) of aperture 101 or Likewise, the flux which flows throughthe portion of the magnetic material of a width taken along a line ee'is equal to the flux 5 which flows through the portion of the magneticmaterial of a diflerent width taken along a line f-f' Likewise, the fluxis equal to the sum of the fluxes which flow in the portions of themagnetic material on each side of the aperture 102, or

For a given total flux 4: the magnetic induction B decreases as thecross-sectional area through which the flux =flows increases, and viceversa. This last relationship results from the fact that B=flux densityor flux per unit area da=a unit area I When a magnetic body has a numberof parallel paths which can be traversed by the flux, then the algebraicsum of the fluxes crossing a surface defined by the intersection of aplane, or other surface, and the body is equal to zero. For instance,referring to FIG. 2b, the irregularly-shaped body of magnetic materialcomprised of a plate 103 has a plurality of distinct flux paths alonglegs 5, 6, 7 and 8 which limit apertures 104, 105 and 106. The plate 103also may be of an irregular thickness. If the positive direction of fluxflow through a plane surface g-g' which passes through the apertures104, 105 and 106 is indicated by the arrow 108, and the negativedirection of flux flow through this surface g-g' is indicated by thearrow 109, then in which each 41 e5 1, and 41 are respectively thefluxes flowing through the plane gg in the legs 5, 6, 7 and 8.

The flux con-figuration of an apertured plate can be changed by sendingexcitation currents through certain of the apertures, for example 104,105, or 106 or FIG. 2b. However, the same relations of continuity offlux flow exist for the changing of the flux as exist for the fluxitself because the condition of continuity always must be satisfied. Thecondition of continuity must be satisfied for any type of material,including a material having a high remanence. However, in order tosimplify the discussion, leakage fluxes in the air are neglected herein,and the flux is considered to be confined to the magnetic materialalone. The simplification is justified because apparatus may be designedor analyzed with sufficient accuracy for practical purposes on the basisof the simplification,

Referring to FIG. 20, a magnetic body comprising an irregularly-shapedplate 12 is provided with apertures 13 and 14. The plate 12 also may beof a variable thickness. A current conductor 11 of n turns (each turn isshown in section) links the magnetic material limiting the aperture 13.A line integral of the magnetic field H along a closed line 16 is equalto the ampere-turns of the electric current passing through the areabounded by the line, or

(5) n'Fj'Hds where H is the magnetic field vector, and ds represents anelemental length of the closed line. Thus, for example, the lineintegral f Hds along the closed line 16 surrounding the aperture 13 isequal to the ampere-turns of the current flowing through the conductor11 which links the line 16. If no excitation current flows through thearea bounded by the line 16, the line integral 'Hds is equal to zero.For example, the line integral f Hds along a closed line 17 surroundingthe aperture 14 is equal to zero because there is no current which linksthe line 17. That the integral is zero does not mean that the magneticfield itself is zero, as the magnetic field may change direction alongthe line 17.

The magnetic induction B is related to the magnetic field H in a mannermost conveniently illustrated by a family of hysteresis loops. Theentire family of majorminor hysteresis loops may be of importance in aparticular application of the transfluxor. The flux configuration isdetermined by (l) the excitation currents; (2) the geometry of thematerial; (3)the major-minor hysteresis loops; (4) the previous historyof the material, and (5) the two basic laws of continuity of flux andequality of the line integral of the magnetic field to the excitationcurrent.

For the moment, assume that the magnetic material exhibits idealrectangular hysteresis characteristics. That is, the hysteresis loopsare assumed to be perfectly rectangular such as the idealized major loopshown in FIG. 3a. He is the symbol for the critical value of magnetizingforce. At a value of +Hc, the magnetic material, if at state N ofsaturation, reverses to the other state P of saturation; at a value of-Hc, the magnetic material, if

saturation.

Referring to FIGS. 3b and 30, a single apertured magnetic body 19 isfabricated from magnetic material assumed to be characterized byperfectly rectangular hysteresis loops. The single aperture 1 8 islimited by the leg 19 on one side and by leg 20 on the other side. Themagnetic body 29 is linked by the winding 21 which is connected to asource of excitation current (not shown). The winding 22 links a portionof the magnetic material, as shown.

If, now, a positive excitation current is applied to the winding 21 inthe direction of arrow h, a clockwise flux flow (as viewed in thedrawing) is produced. Upon removal of the positive excitation current,the legs 19 and 20 are saturated in the state P of saturation atremanence. The clockwise sense of flux flow in the legs 19 and 20 isindicated by the solid arrows 23 and 24. Now, if a negative excitationcurrent is applied to the winding 21 in the direction of arrow h, acounter-clockwise flux flow is produced. Upon removal of the negativeexcitation current, the state of saturation at remanence of the legs 19and 20 is reversed from the state P to the state N. Thecounter-clockwise sense of flux flow in the legs 19 and 20 is indicatedby the dotted arrows 25 and 26.

The state of saturation at remanence of the legs 19 and 20 is reversedrepeatedly by the application of alternate positive and negativeexcitation currents to the winding 21. A change of flux from one of theclockwise or counterclockwise senses to the other induces a voltage inthe coupled winding 22.

Consider the flux configuration of the magnetic body 29, as shown inFIG. 30, in which it is supposed that somehow one leg 19 is at a state Pof saturation at remanence, resulting from a flux flow in the clockwisesense, as indicated by arrow 23, the other leg 20 is at a state N ofsaturation at remanence resulting from flux flow in the counterclockwisesense, as indicated by arrow 26. Now, if a positive or negativeexcitation current is applied to winding 21, no change of flux isproduced because the leg 19 already is saturated in the clockwise senseand the leg 20 already is saturated in the counterclockwise sense.Consequently, the back and forth or A.C. excitation current applied towinding 21 does not induce a voltage output in secondary winding 22.

Therefore, if it were possible to saturate the legs 19 and 20selectively in the same state of saturation at remanence, or in oppositestates of saturation at remanence, as indicated in FIGS. 3b and 3c,respectively, then the singleaperture magnetic circuit would be able tocontrol the flux flow so as to produce, or not to produce, an outputvoltage in winding 22 in response to the excitation currents applied tothe winding 21. This simple arrangement of FIG. 312 or 30 then wouldoperate as a transfluxor. However, it is apparent from the theoryexpounded that the flux configuration of the magnetic circuit shown inFIG. 30 violates the condition of continuity of flux flow because thealgebraic sum of fluxes through the surface indicated by the line k-k'is not equal to zero.

The condition of continuity of flux flow likewise would be violated ifthe two legs 19 and 20 of the magnetic circuit of FIG. 30 were eachsaturated in the states of saturation at remanence opposite from thoseshown, with the leg 19- at a state N and the leg 20 at a state P ofsaturation at remanence. While it is impossible in principle -tosaturate the legs of a single-aperture magnetic circuit in oppositestates of saturation at remanence along a selected path, such saturationis readily accomplished in accordance with the present invention in atransfluxor having at least two apertures.

For example, in connection with FIG. lb, observe the states ofsaturation of the legs 2 and 3 in each case with reference to theintermediate aperture 34 of the transfluxor described. In one case, thelegs 2 and 3 are saturated in the same state of saturation at remanencewith respect to the aperture 34, that is, with respect to the selectedpath immediately about the aperture 34 as shown 10 by the dotted arrowin the leg 2 and the solid arrow inf the leg 3. On the other hand, inthe other case, the legs, 2 and 3 are saturated in opposite states ofsaturation at remanence with respect to the intermediate aperture 34,as, shown by the solid arrows in the legs 2 and 3. Thus, by selectivelyapplying a positive or a negative excitation current to the winding 33,the legs 2 and 3 are selectively saturated in the same or oppositestates of saturation at remanence with reference to the intermediateaperture 34.

Practical materials deviate somewhat from the idealmaterial which hasbeen assumed to have perfectly rectangular hysteresis loops. However,with actual materials having non-ideal rectangmlar hysteresis loops, therectangularity of the loops is suflicient to provide the desired resultsin practice. FIGURE 10 is a graph of the major hysteresis loop of atypical sample of the rectangular hysteresis loop magnetic material usedin fabricating a transfluxor.

Referring to FIG. lb, assume that an excitation current in the directionof arrow a is applied to winding 33 to set up the flux configurationshown by the solid arrows in the legs 2 and 3, with leg 2 at a state Pof saturation at rcmanence and leg 3 at a state N of saturation atremanence with reference to aperture 34. Because the legs.

are substantially equal in cross-sectional width, the hysteresis loopfor leg 2 is substantially identical to the hysteresis loop for leg 3.The hysteresis loops for the legs 2 and 3 are superimposed and becomethe hystermis loop of FIG. 10. The point P of FIG. lc represents thestate of saturation of leg 2 and the point N represents the state ofsaturation of leg 3. Thus, if an excitation current is applied towinding 35 in the direction of arrow b so as to produce a clockwisemagnetizing force which tends to establish a clockwise flux flow, thenthe magnetizing force tends to magnetize both legs 2 and 3 towards thestate P with reference, to aperture 34. The. magnetomotive forceequation for a plate of uniform thickness can be expressed as follows:

where the term ni is the ampere-turns linking the flux path aroundaperture 34; is the length of the flux path along the leg 2 or along theleg 3, both legs being of equal length; and H and H are, respectively,the magnetizing forces applied to the legs H and H The effect of themagnetizing force on the legs 5 and '6, which also are a part of themagnetic material limiting the aperture 34, is neglected in the aboveequation but may be considered as being incorporated with either one orthe other, or both, of the legs 2 and 3, if desired.

Referring again to FIG. 10, the changes in flux A and Mi produced inlegs 2 and 3, respectively, must be equal because the flux flow iscontinuous; that is,

The changes in flux flow in the legs 1 and 4 are neglected for thereason that the amplitude of the excitation current applied to winding35 is assumed to be insutficient to cause any appreciable flux flowaround those longer flux paths which encompass the aperture 34 alongwith either one or both of the apertures 32 and 36.

In order tosatisfy both the magnetomotive Equation 6 and the flux changeEquation 7, the magnetic fields take values H and H shown in FIG. 10. Ifthe hysteresis loop were perfectly rectangular (i.e., the legs perfectlysaturated), then A =A =0. The magnetic field H also would be equal tozero, and IE would be equal the ampere-turns ni However, with imperfect,actual materials, the small changes in flux A 5 A are not equal to zero.Even if the polarity of the excitation current applied to winding 35 of.aperture 34 is reversed, no, or at most a small, change of flux results.Therefore, backand-forth excitation of the magnetic material limitingaperture 34 produces no appreciable change of flux on leg 6, hence no,or at most a small, voltage is induced in the output winding 39 whichlinks leg 6.

Now consider the condition where the legs 2 and 3 are both saturated inthe N state of remanence with respect to aperture 34. When an excitationcurrent in the direction b is applied to the winding 35, there is achange from the state N of saturation at remanence, represented by thepoint N of FIG. llc, for both the legs 2 and 3, to a state P ofsaturation. Thus, the change of flux Q50, after the excitation forcereturns to zero, may be represented by the distance between the points Nand P FIG. lc. This latter change of flux is much greater than eithervalue A or A Consequently, signals induced in the output coil 39 by thechange of flux are readily distinguished from the smaller signalsinduced by A or A Discrimination against the latter signals may be madesubstantially complete.

Inconsidering the hysteresis loop diagram of FIG. 10 heretofore, theconvention was adopted that when the sense of saturating flux flow inthe flux path around aperture 34 was clockwise, the state of saturationwas P and, conversely, when the sense of saturating flux flow in theflux path around aperture 34 was counter-clockwise, the state ofsaturation was N. The flux changes may also be considered by using theconvention that positive and negative directions of flux flow existthrough a surface which intersects some or all of the apertures of amagnetic body, such as the plane surface represented by the line gg' inFIG. 2b. The latter convention leads to a simple, graphical constructionof flux changes. For instance, FIG. la illustrates a graphical method ofdetermining the flux flow conditions through the two legs 2 and 3 of themagnetic circuit when the direction of flux flow in the two legs is thesame. When both legs 2 and 3 are magnetized, as shown by the solidarrows of FIG. 1b, the direction of flux flow in each of the two legs ispositive, and the state of saturation at remanence of each legrepresented by a point such as the point P of FIG. 1 The hysteresisloops for the legs 2 and 3 are substantially identical, and thehysteresis loop of FIG. 1d may be considered as the hysteresis loop forone leg superimposed upon that for the other. Suppose that a magnetizingforce in the clockwise sense (current in the direction b) is applied tothe winding 35 of FIG. 1b. This force shifts the point representing inFIG. 1d the magnetic state of the leg 2 fromthe position P in a positivedirection along the hysteresis loop. At the same time, this force shiftsthe point representing the magnetic state of the leg 3 from the positionP in a negative direction along the hysteresis loop. It is a conditionof the magnetic circuit that the of the magnetizing forces be equal tothe driving ampere turns ni, as in the case for Equation 6. Properweighing factors relating to the lengths of-the legs should be employed.In the instant case, the factors are unity because the legs 2 and 3 areequal. Therefore, the sum of the magnetizing forces is the sum of themagnetic fields H and H A second condition of the magnetic circuit isthat the values for change of flux must be equal, Equation 7. Therefore,graphically, a point is found on the hysteresis loop to the left of Pand another point to the right of P satisfying the two conditions, asillustrated in FIG. 1d. The graphical method of flux determination canbe extended to more legs, if desired.

1 Referring to FIG. 1b, it is now apparent that the respouse in theoutput winding 39 to the excitation current applied to the winding 35can be considered to depend upon the states of saturation at remanenceof legs 2 and 3. A relatively high-level response is obtained when bothlegs have the same state of saturation along a flux path around aperture34. A negligible, or relatively low-level, response is obtained whenboth legs have opposite states of saturation with reference to theaperture 34. 'The reference excitation current applied to winding 37sandthe current applied to winding 33 control whether 12 the legs 2 and 3have the same or opposite states of saturation with reference to theaperture 34.

The magnetic material limiting aperture 36 may be saturated initially ina reference state, for example, in the state P with clockwise flux flowwith reference to the aperture 36. Leg 4 may then remain saturated inthe reference state of saturation at remanence, with a downward(negative) direction of flux flow. The response to the excitationapplied to winding 35 is indicative of the state of saturation atremanence of leg 1. The excitation of the magnetic material limitingaperture 34 leaves the state of saturation at remanence of leg 1unaltered under the conditions set out hereinbefore. Therefore, thetransfluxor can be used for storing a binary digit where the states (Pand N) of saturation at remanence of leg 1 respectively represent abinary one and a binary zero, or vice versa. For example, a binary onecan be written into the transfluxor by applying a positive excitationcunrent to winding 33 of aperture 32 to establish leg 1 in a state P ofsaturation at remanence with reference to aperture 32. A binary zero canbe written into the transfluxor by applying a negative excitationcurrent to winding 33 to establish leg 1 in a state N of saturation atremanence. The stored information is then read out of the transfluxor byapplying a positive excitation current to winding 35 of aperture 34 andobserving the voltage induced in winding 39. A relatively high voltageindicates a binary one is stored, and a relatively low, or no, voltageindicates a binary zero is stored in the transfluxor. In practicalcircuits, the high voltage may be five or more times greater inamplitude than the small voltage.

The read-out can be termed non-destructive because it leaves the storedinformation available to be read repeatedly by excitation of winding 35.However, the flux of legs 2 and 3 is, in fact, changed to obtain theread-out signal. The voltage induced in the output winding 39 is due tothe change of flux in legs 2, 3, 5 and 6. Nevertheless, the originalstates of the changed legs 2, 3, 5 and 6 are restored by applying anopposite (negative) excitation to winding 35 of aperture 34. Thenegative excitation current is applied to winding 35 regardless ofwhether a read-out signal indicates a binary one or a binary zero. Inthe case of a binary zero, neither the positive nor the negativeexcitation current applied to winding 35 of aperture 34 changes thestates of saturation at remanence of the legs 2 and 3.

Another way of describing the eflfect is to consider the informationdigit as being stored in the leg 2 rather than the leg 1. Theinformation digit is written in the leg 2 by applying an excitationcurrent to the winding 33 of the aperture 32 which leaves the state ofsaturation at remanence of the leg 3 unaltered. Thus, when an AC.excitation current is applied to the winding 35 of the aperture 34, thestate of saturation at remanence of the leg 2 is either reversed or not.If the saturation of the leg 2 is reversed by either one of the phases,then its original state of saturation is restored automatically on thenext phase, without need for any feedback circuitry, thereby insuring aneffective, non-destructive read-out. On the other hand, if thesaturation of the leg 2 is not reversed by the one phase, then, on thenext phase, the opposite excitation leaves its state of saturationunaltered. Therefore, the leg 2 is subjected to the unconditionalrestoring excitation without losing the information stored therein. Thelatter way of looking at the phenomena is the more realistic, becausethe state of saturation at remanence of leg 1 plays no role, per se, inthe read-outprocess. Leg 1 is significant in allowing the setting of leg2 to a state of saturation at remanence without changing the state ofsaturation at remanence of leg 3. From another viewpoint, however, leg 1provides a bypass or shunt magnetic circuit for the flux. After leg 2 isset to a state of saturation at remanence, the magnetic state of leg 1may be changed by still another aperture".

13 to the left of aperture 32, and the reading effects, inso- 'ar asaperture 34 is concerned, would remain unaltered.

The controlled excitation current which is passed hrough aperture 34maybe an indefinite sequence of rairs of positive and negative currentpulses, that is, an \.C. signal, which terminates upon a complete cycle.The 'esulting read-out signal then exists indefinitely for one :ense offlux flow around aperture 34 and is essentially zero for opposite sensesof flux flow around the aperture {4. The pairs of positive and negativecurrent pulses reed not be regularly spaced in time.

Both electronic flip-flops and magnetic toroids or cores rave beenemployed for storing binary digits. The fliplop is able to furnish acontinuous indication of the tored information, 'but requires acontinuous holding rower while performing the storing function becauseone )r the other of its tubes must be fully conducting. The magnetictoroids' can store information indefinitely with- :ut requiring holdingpower. However, the information :tored in. a. toroid is destroyed by thevery process of 'eading it out, and if the information is to beretained, in extraneous feed-back circuit is required. Thus, theransfluxor has the advantages of both the electronic lip-flops and themagnetic toroids. The transfluxor can tore information indefinitelywithout requiring holding rower, and the information stored in thetransfiuxor can re repeatedly read out without destroying it.

An important property of the magnetic system de- :cribed in connectionwith FIG. 1b is that the write-in ind read-out information areindependent. That is, the vrite-in resulting from the application of anexcitation :urrent to the write-in winding 33 of aperture 32 does rotcause a voltage to be induced in output winding 39 aecause the flux flowis confined to the magnetic material imiting aperture 32. Similarly, theinterrogating cur- ."ents applied to winding 35 of aperture 34 do notcause 1 voltage to be induced in the write-in winding 33 because he fluxflow is confined to the magnetic material limiting aperture 34.

IMPROVED SIGNAL-TO-NOISE RATIO In the operation described above, if thevoltage induced in the output winding 39 when the flux configuration ofthe magnetic system is as indicated in FIG. 1b by the solid line arrows,and corresponding to the change of flux A =A this voltage results in anunwanted or noise signal. This noise signal is due to the imperfectlyrectangular hysteresis characteristics of the magnetic material.

This output noise signal may be at least partially can- :elled in thetransfluxor by arranging the winding 39 to link both of the legs 3 and4, as shown in FIG. 4a, or to link the three legs 3, 4 and 7, as shownin FIG. 4b. [11 the embodiment of FIG. 4a, the output winding 39 may bethreaded downwardly through the aperture 34, then in back of the leg 3,then upwardly through the aperture 36, then around the leg 4, and againupwardly through the aperture 36. In the embodiment of FIG. 4b, theoutput winding 39 is threaded downwardly through the aperture 32, behindand around the leg 7, downwardly through the aperture 34, behind the leg3, then upwardly through the aperture 36, then around the leg 4, andfinally upwardly through the aperture 36 again. The cancellation ofnoise in the embodiment of FIG. 4a arises from the fact that the changesof flux in legs 3 and 4 induce cancelling voltages in the output winding39. In the arrangement of FIG. 4b, an additional noisecancelling voltageis induced in the output winding 39 due to the linking of the leg 7thereby. Although the noise cancellation with the arrangements of FIGS.4a and 4b is only partial, because most of the flux flows directlyaround the aperture 34, these arrangements, in practice, improve thesignal-to-noise ratio markedly. A good signal-to-noise ratio is alsoobtained by arranging the, output winding 39 to link the leg 3 only, asshown 14 in FIG. 40. For this purpose, the winding 39 is threadeddownwardly through the aperture 34, behind the leg 3, and then upwardlythrough the aperture 36. In the arrangement of FIG. 40, the flux changesin the legs 1 and 4 do not contribute to the voltage induced in thewinding 39, and hence do not affect the output signal.

TWO-APERTURE TRANSFLUXOR The aperture 36 of the three-aperturetransfluxor of FIG. 1b is a dummy aperture and plays the role of areference in the case of the three-aperture transfluxor. Referring toFIG. 5a, there is shown a two-aperture transfluxor fabricated of arectangular plate 40 of substantially homogeneous magnetic materialcharacterized by a substantially rectangular hysteresis loop. The plate40 has two apertures 41 and 42, to provide a center leg 50 and side legs49 and 51. The crossasectional widths of the leg 51 along the line e-e'through the centers of the apertures 41, 42 are equal to, or greaterthan, the sum of the cross-sectional widths of the side legs 49 and 50along the same line. The cross-sectional widths W and w; (FIG. 5b) ofthe top and bottom links 52 and 53 which connect the side legs 51 and 52are each equal to the cross-sectional width (along the line e--e) of leg51. It is not necessary that the plate be of a uniform thickness,although for convenience FIG. 5b shows the thickness (t to be uniform. Awinding 43 links the magnetic material limiting the aperture 41, and adiiferent winding 44 links the magnetic material limiting the aperture42. The winding 43 is connected to a, pulse source 4.7,, and. thewinding 44 is connected to an AC. source 46. An output winding 45 linksthe magnetic material comprising the middle leg 50, and a load device,

48 is connected across the winding 45. A 43a links the material limitingthe aperture 42. The winding 43a is also connected to the pulse source47. In FIG. 5a, current flow in the windings 43, 43a, and 44 is taken aspositive when in the direction of the arrows adjacent the respectivewindings.

The two aperture transfluxor is capable of several different modes ofoperation, for example, either to transmit or to block signals. Two suchmodes will now be described in accordance with the following outline:

Mode I (a) Transfluxor in signal-passing condition (b) Transfluxior insignal-blocking condition Moa'e II (a) Transfluxor in signal-passingcondition (b) Transfluxor in signal-blocking condition OPERATION OFTWO-APERTURE TRANSFLUXOR Mode I (a) TRANSFLUXOR IN SIGNAL-PASSINGCONDITION In the first mode, the windings 43 and 43a, through theaperture 41, are. used for controlling the response to the input signalfurnished by the AC. source 46. The output of an AC. source 46 isapplied to the winding 44 which is located between the narrow middle leg50 and the wide leg 51. Initially, assume that a relatively intensenegative excitation current is applied by the pulse source 47 to thewinding 43a, thereby establishing a counter-clockwise flux flow in theflux path around the aperture 42. Because of the intensity of thisnegative excitation current, a flux flow in the counter-clockwise sensewith reference to the aperture 42 is also established in the narrow sideleg 49. The sense of flux flow is shown by the solid arrows. When theintense negative excitation current is terminated, the narrow legs 49and 50 are in a state N of saturation at remanence and the leg 51 in astate P of saturation at remanence with reference to the direction offlux flow through a horizontal plane represented by the center linee-e'. The states of saturation at remanence oi the three legs 49, 50 and51 are convenient-- ly represented by points on their respective,somewhat idealized hysteresis loops shown in FIGS. 50, d and 5 Thesethree hysteresis loops correspond to the magnetic characteristics of thelegs 49, 50 and 51, respectively. After the relatively intense negativeexcitation current of winding 43a is terminated, the legs 49, 50 and 51are in states represented by the points 1-1, Z-l, and 3-1 on theirrespective hysteresis loops. The flux contlmuty relation for thetransfluxor of FIG. 5a may be expressed where e5 and 3 are the algebraicvalues of the fluxes passing through the surface of the horizontal planee-e' in the respective legs 49, 50 and 51.

The hysteresis loop of FIG. 5e for the wide leg 51 is not as rectangularas those of FIGS. 5c and 5d for the narrow legs 49 and 50 because thevalue of magnetizing force H is less uniform for the wide leg 51 thanfor the other two legs. The strength of the magnetizing force H isgreater near aperture 42 and weaker farther out. As previously noted,the closed line integral of the magnetic field is equal to theamperelurns of the electric current passing through the area hounded bythe line. Accordingly, if the lines of the magnetic field are consideredto be circular, then the magnetizing force varies inversely with theradial distance from the winding 44, which explains the lesser intensityof field for the wide leg 51.

The hysteresis loops for the legs 49 and 50 are shown to diifer somewhatin height along the axes because initially the magnetizing force exertedon the leg 49 is less than the magnetizing force exerted on the leg 50when an excitation current is applied to the magnetic material limitingthe aperture 42.

Assume, now, that a positive excitation current is applied to thewinding 44 by A.C. source 46. This positive excitation current isrestricted to an amplitude much less than the initial negativeexcitation current. By much less is meant, for example, iirorn a thirdto a quarter of the initial value or negative excitation current in thewinding 43a. As a result of this relatively weak, positive excitationcurrent the winding 44, the saturating flux in the leg 50 reverses fromthe counter-clockwise sense to the'cloclnwise sense reference to theaperture 42. The clockwise saturating lines of flux in the leg 51 eitherdiminish or reverse to an extent suflicient to satisfy the basic-fluxcontinuity equation. Now, the states of saturation of the narrow legs 50and 51 are represented by the points 2-2 and 3-2 on their respectivehysteresis loops, as shown in FIGS. 5d and 5e, but the leg 49 remains inthe state N of saturation at remanence represented by a point 1-2 at orvery close to the point 1-1 on its hysteresis loop of FIG. 50. Thus, theflux is balanced at remanence, that is, the flux flow Equation 8 issatisfied, by reversing the flux flow to the P direction in the leg 50and decreasing or reversing the flux flow in the leg 51. The leg 49,however, changes its state of saturation at remanence slightly, at all,because it is subjected only to a slight positive magnetizing forcewhich may cause a small clockwise flux flow due to the imperfectrectangularity of the hysteresis loop or the magnetic material. ThediflEerence in flux ordinates between the points 3-1 and 3-2 of FIG. 5efor the leg 51 is substantially equal to a line difierence between thepoints 2-1 and 2-2 of FIG. 5d tor the leg 50.

During the change of flux in the legs 50 and 51 just described, avoltage is induced in the output Winding 45 which links the leg 50.Thereafter, a positive excitation current in the winding '44 is followedby a negative excitation current. The states of saturation of the legs50 and 51 change again and now may be represented by the points 2-3 and3-3, respectively, on the hysteresis loops of FIGS.- 5d and 5e. Thepoints 2-3 and 3-3 are sub-- stantially the same as the points 2-1 and3-1, respectively. The intensity of the subsequent positive and negativeexcitation currents in the winding 44 may be maintained at a suitablevalue below that at which the resultant magnetizing force causes anappreciable flux fiow in the leg 49. With each of the negativeexcitation currents applied to the winding 44, some additionalcounterclockwise flux does flow in the leg 49. However, when thenegative excitation current in the winding 44 is terminated, the leg 49resumes, substantially, its initial state of saturation at remanencebecause the change from the state N of saturation to increasedsaturation in the N direction and return is substantially reversible.During these reversals, a point representing the magnetic state of theleg 49 describes a minor hysteresis loop that includes the points 1-1,1-2, and 1-3.

The reversals of the states of saturation at remanence of the legs 50and 51 can now be repeated indefinitely. In that event, the magneticstates of the legs 50 and 51 alternate between states represented by thepoints 24, 2-3 and 3-1, 3-3, respectively. Meanwhile, the leg 49 remainsin the magnetic state represented by a point at or near the point 1-1,as just explained. An output voltage is induced in the output winding 45during each reversal of flux in the leg 50 and, consequently, an A.C.output voltage is supplied to the load device 48.

OPERATION OF TWO-APERTURE TRANSFLUXOR Mode I (b) TRANSFLUXOR INSIGNAL-BLOCKING CONDITION Assume, now, that after the negativeexcitation current in winding 43a, a relatively intense positiveexcitation current is applied to the winding 43 by the pulse source 47.The intensity of this last, positive excitation current applied to thewinding 43 is sufficient to establish a clockwise flux flow around thelonger flux path indicated by the dotted line 56 which encircles boththe apertures 41 and 42. When this intense, positive excitation currentis terminated, the side legs 49 and 51 are, respectively, in states ofsaturation at remanence represented by points 1-4 and 3-4 on thehysteresis loops of FIGS. 5c and 5e. The state of saturation atremanence of the leg 50 remains unchanged because the leg 50 is alreadysaturated in the N state, with flux flowing in the clockwise sense withreference to the aperture 41. Thus, the state of saturation at remanenceof the leg 50 remains at N, as represented by the point 2-4 of FIG. 5d.

Now, when the relatively weak, positive excitation current is applied towinding 44 of aperture 42, substantially no change of flux occurs in anyleg. The lack of change of flux is due to the fact that the leg 49 isalready saturated in the clockwise sense with reference to the aperture42, so that any change of flux in the leg 50 would require acorresponding change in leg 51. However, leg 51 is already in a state ofsaturation at remanence (for example, such as state 3-4 as shown on thehysteresis loop diagram of FIG. 5e). The state 3-4 is a saturated stateeven though the flux flow in this state of remanence is close to, oreven equal to zero. It, then, an attempt is made to magnetize leg 51negatively (leg 51 being in the state corresponding to the point 3-4),very little change of flux occurs, and whatever change does occur isalmost entirely reversible. It appears that operation is along one ofthe minor rectangular hysteresis loops. Actually, because the hysteresisloops are not perfectly rectangular or, in other words, because thesaturation elrect is not perfect, the legs 50 and 51 do change slightlyand assume states represented by the points 2-5 and 3-5, as shown inFIGS. 5d and 52.

If the relatively weak, positive excitation current pulse applied to thewinding 44 is followed by a relatively weak negative excitation currentpulse, then again substantially no change of flux. occurs. In thislatter situation, the center leg 50 does not change state because it isalready saturated ith flux in the counter-clockwise sense with referenceto the aperture 42. The side legs 49 and 51 can only change with astronger excitation current exerting a magnetomotive force around thelonger flux path 56 of FIG. a. Therefore, ideally, with the relativelyweak, negative excitation current, no change occurs. As a practicalmatter, however, due to the imperfect rectangularity of the hysteresisloops, small, minor hysteresis loops are described. States correspondingto the points 2-6 and 3-6 of FIGS. 5d and 6e, which are substantiallyequivalent to the states 2-4 and 3-4, respectively, are now assumed bythe legs 50 and 51. A train of positive and negative excitation currentpulses applied to the winding 44 of the aperture 42, therefore, inducesvery little, or no, output voltage in the output winding 45. The initialstates of saturation of the legs 49, 50' and 51 may now be reproduced byapplying a relatively intense, negative excitation current to thewinding 43a. The legs 49, 50 and 51 are then saturated again at thestates represented by the points 1-1, 2-1 and 3-1 on the hysteresisloops of FIGS. 50, 5d and 5e. Thus, following the initial negativesetting excitation current pulse applied to the winding 43a, themagnetic system of FIG. So does, or does not, furnish an output signalin the output winding 45 in response to a subsequent train of weakerpositive and negative excitation current pulses depending upon thecontrol signal applied to winding 43. When a positive excitation currentpulse is applied to winding 43, a very small, or no, voltage is inducedin the output winding 45. Note that the positive excitation currentpulses applied to the winding 43 do not cause a flux flow in the leg 50,and hence no output voltage is induced in the winding 45 which links theleg 50. Therefore, the control circuit and the controlled circuit arevirtually independent of each other. The control excitation current inthe twoaperture transfluxor of FIG. 5a are larger in amplitude thanthose required for the three-aperture transfiuxor because the amplitudeof the control excitation currents should be sufficient to establish asaturating flux flow around the longer flux path 56 (FIG. 5a).

The two-aperture transfluxor may also be used for storing binaryinformation. For this purpose, the signal transmitting condition of thetransfiuxor resulting from application of the negative setting currentapplied to the winding 43a may correspond to a binary one. Thesignal-blocking condition of the transfiuxor resulting from the positiveexcitation current applied to the winding 43 may correspond to a binaryZero. The winding 44 may be employed, instead of the winding 43a, toapply an intense, negative excitation current to place the transfluxorin the binary one condition. If desired, the pulse source 47 may be abinary device, for example, a flip-flop circuit, connected to apply apositive pulse to the Winding 43 when assuming one binary state and toapply a negative pulse to the winding 43a when assuming the other binarystate. The transfluxor then assumes one condition or the othercorresponding to one binary state or the other of the pulse source 47.

The stored binary information can be read out by applying a positive andnegative sequence of excitation pulses to the winding 44 and observingthe voltage induced in the output winding 45. When a binary zero isstored a small, or no, change of flux flows in the leg 50; hence, asmall, or no, voltage is induced in the winding 45. When a binary one isstored, a flux change is produced for each excitation pulse of thesequence, and a relatively large voltage is induced in the winding 45.The read-out may be continued for an indefinitely long sequence ofreading excitation current pulses without destruction of the storedinformation.

Ideally, the two-aperture transfluxor does not respond to an excitationcurrent applied to the winding when the states of saturation of the legs49, 50 and 51 correspond to the points l-4, 2-4 and 3-4, respectively,as i1- lustrated on the hysteresis loop-s of FIGS. 50, 5d and 5e.However, it is probable that some change of flux is produced in the wideleg 51' by the relatively weak excitation currents of the winding 44because of the imperfect rectangularity of the hysteresis loops. Duringthese weak excitation currents, a point representing the magnetic stateof the wide leg 51 describes a minor hysteresis loop of FIG. 52. Thischange of flux is perhaps larger than that which would occur if the leg51 were narrow and fully saturated at state N of saturation ofremanence. In any event, as explained in connection with a similarchange of flux in the magnetic system of FIG. 1b, this change in fluxresults in a noise signal.

It is possible to improve the sign-al-to-noise ratio in the two-aperturetransfluxor by a modification such as shown in FIG. 5 This modificationinvolves splitting the wide leg 51 by a third aperture 61 to provide afourth leg 62 in the plate 40 such that all of the legs 49, 50, 51, and62 are of equal width. A flux fixed in direction and magnitude isestablished in the leg 62 by applying a setting excitation current pulseto the winding 43a of the aperture 42. This setting excitation currentpulse is sufficient in amplitude to produce a saturating flux flowaround all of the apertures 41, 42 and 61.

Suppose, now, that a positive pulse is applied to the winding 43 ofsufiicient amplitude to reverse the states of saturation of the legs 49and 51, but not sufficient to aifect the state of saturation of the leg62. The transfluxor of FIG. 5 is then in the signal-blocking condition.The leg 50 is already saturated in the clockwise sense with respect tothe aperture 41. Moreover, because the last-mentioned positive pulse isnot of suflicient amplitude to cause the flux to pass around theaperture 61, all of the change of flux in the leg 49 appears as a changeof flux in the leg 51. Accordingly, the leg 51 is saturatedsubstantially completely with substantial flow of flux in the clockwisesense around the aperture 41. Consequently, when alternate, Weakpositive and negative current excitation pulses are applied to thewinding 44, the legs 50 and 51 are in opposite states of saturation withrespect to the aperture 42. However, notice that the leg 51 now has asubstantial flux flow. A point representing the magnetic condition ofthe leg 51 during the alternate positive and negative current pulses inthe winding 44, therefore, describes a minor hysteresis loop near apoint, such as point P, on a larger hysteresis loop. A minor hysteresisloop at the point P, which indicates a greater flow of flux, however,has less amplitude along the axis for a like amplitude along the H axis.Accordingly, less noise signal is induced in the output Winding 45. Theoperation of the transfluxor of FIG. 5) in other respects will beunderstood by those skilled in the art from the preceding description ofthe transfluxor of FIG. 5a.

OPERATION OF TWO-APERTURE TRANSFLUXOR Mode 11 (a) TRANSFLUXOR INSIGNAL-PASSING CONDITION In explaining the operation of the transfluxorshereinbefore described, it was emphasized that the amplitude of thecontrolled or read-out output currents is limited to a certain definitemagnitude. The limitation arises because the magnitude of the currentsof the AC. source should not be greater than that which establishes aflux flow in the relatively short path around one aperture. In the firstmode, when it is desired to load the output circuit in order to obtain arelatively large output current, a correspondingly large excitationcurrent would be needed on the unblocked condition. Such a largeexcitation current, however, in the blocked condition would exceed thelimit mentioned above, and would cause flux flow in the longer pathwhich would unblock the transfiuxor. Therefore, such large loads andsuch large excitation currents are not used in the first mode.

The following described asymmetrical mode of opcrating a two-aperturetransfluxor provides an output signal of a much larger amplitude thanthat for modes of operation described heretofore for like-sizetransfluxors. Referring to FIG. 6a, there is shown a two-aperturetransfluxor similar to that of FIG. a having an output winding 54instead of the output winding 45 of FIG. 5a. The output winding 54 linksthe leg 49 and is coupled to a load 55. Instead of the AC. source beingcoupled to the winding 44, as in FIG. 5a, the winding 44 of FIG. 6a iscoupled for polarity reversal through a double-pole, double-throw switch58 to a battery 60, and a series resistance 125. A single-throw,single-pole switch 59 is interposed in the connection between thebattery 60 and the switch 58. A pulse source 47a is connected to thewinding 43. The winding 43a of FIG. 5a and the pulse source 47 need notbe employed in the arrangement of FIG. 6a.

In operation, the arm of the reversing switch is thrown down (as viewedin the drawing), and the switch 59 is closed and opened, thereby toprovide a negative excitation current pulse 64:: (illustrated in FIG. 6to the winding 44 of FIG. 6a. A flux flow is established in the legs 49,50 and 51 in the counter-clockwise sense about the aperture 42. Thepoints L1, K1 and L1 represent the states of saturation at remanance ofthese legs on the respective hysteresis loop diagrams of FIGS. 6b, 6cand 6d. The pulse source 47a supplies to the winding 43 a sequence ofcurrent pulses of waveform 63 (FIG. 6e). The waveform 63 consists of anintense, positive excitation current pulse 63a followed by a weak,negative excitation current pulse 63b. The direction of flux flow inFIG. 601, as distinguished from the sense of flux flow around theapertures, is taken with respect to the horizontal plane ff through theapertures 41 and 42.

The first positive pulse 63a establishes a clockwise flux flow withreference to the aperture 41 in the longer path 56 about both of theapertures 41 and 42. Accordingly, after the first pulse 63a isterminated, the leg 49 is in a state P of saturation at remanancerep-resented by the point 1-2 of FIG. 6b; the leg 50 is in a state N ofsaturation at remanence represented by the point K-2 of FIG. 60, becausethe sense of flux flow in leg 50 is already clockwise with reference tothe aperture 41; and the leg 51 is at a state of saturation at remanancenear zero flux flow represented by the point L2 of FIG. 6d. Theintensity of the current pulse 63a (FIG. 62) is not only suflicient toprovide the saturating lines of flux along the longer path 56 (FIG. 6a)which encircles both apertures 41 and 42, but also to counterbalance thedemagnetizing tendency of the output current induced in the outputwinding 54.

The next succeeding weak, negative excitation current pulse 63b (FIG.62) establishes a counter-clockwise flux flow about the aperture 41(FIG. 6a). After this current pulse 63b is terminated, the legs 49 and50 are in states N and P of saturation at remanance, respectively,represented by the points 1-3 and K-3 of FIGS. 6b and 6c. The leg 51 isin a state of saturation at remanance represented by the point L-3 ofFIG. 6d, substantially without change, because the intensity of thenegative pulse is insufficient to establish a flux flow about the longerpath 56 of FIG. 6a. The saturation states of the legs 49 and 50 arereversed.

During a reversal of the flux in the leg 49 from a clockwise to acounter-clockwise sense of flux flow, an output voltage is induced inthe output winding 54 and which is capable of producing a demagnetizingload current. In order to insure that the less intense, negativeexcitation current pulse provides sufficient magnetizing force toreverse the sense of flux flow in the legs 49 and 50 in spite of thedemagnetizing load current, the rise time of the power-producing pulse63a (FIG. 62) and also, as a practical matter, the decay time is mademuch shorter than that of the negative excitation current pulse 63b. Therise and decay times of either the pulse 63a,

or the pulse 63b, may be, but need not be, the same. However, theleading edge of either pulse is more significant than the trailing edgeof the same pulse, because the trailing edge terminates the pulse andleaves the magnetic material in a state of saturation at remanence,whereas the leading edge causes reversal of the magnetic state of thematerial and supplies the load current.

A new power pulse 63a again establishes a clockwise flux flow in thelegs 49 and 5th with respect to the aperture 41, and these legs assumethe states P and N of saturation at remanence, respectively, representedby the points J4 and 51-4 of FIGS. 6b and 6c. Also, the magnetic stateof the leg 51, represented by the point L-4 of FIG. 6d, is practicallyunaltered. Thus, the legs 49, 50 and 51 are returned to substantiallythe same states of saturation as existed immediately after the previous,positive power pulse which was applied to the winding 43 (FIG. 6a). Asubsequent, relatively weak, negative excitation pulse 63b (FIG. 60)again establishes a counter-clockwise flux fiow in the path 57 (FIG. 6a)around the aperture 41. The legs 49, 50 and 51 are now in the states ofsaturation represented, respectively, by the points J-S, K-S and L-S ofthe respective hysteresis loops of FIGS. 6b, 6c and 6d.

It is therefore apparent from the foregoing that, after the initial,negative setting pulse has been applied to the winding 44, the effect ofthe sequence of a positive power pulse, followed by a less intensenegative pulse, is to reverse the sense of saturating flux flow in theleg 49 for both the positive and the negative pulses, and to supply tothe load 55, for each positive pulse, a relatively large output currentpulse.

The flux in the leg 51 changes by a substantial amount only at the firstpositive pulse applied to the winding 43. For all subsequent positiveand negative pulses applied to the winding 43, for a change of flux inone of the legs 49 or 50, there is a substantially equal change of fluxin the other one of these legs. There is, at the same time, only asmall, or no, flux change in the leg 51. The points J5, K-S and L-5 ofthe respective hysteresis loops of FIGS. 6b, 6c and 60! represent,respectively, the states of saturation at remanence of the legs 49, 50and 51 following any sequence of pairs of the positive and negativepulses.

OPERATION OF TWO-APERTURE TRANSFLUXOR Mode II (b) TRANSFLUXOR INSIGNAL-BLOCKING CONDITION Consider, now, the effect of a positiveexcitation current pulse which is applied to the winding 44 (FIG. 6a).The arm of the reversing switch 58 is thrown up (as viewed in thedrawing) and the switch 59 is closed and opened, thereby to provide apositive excitation current pulse 64b (illustrated in FIG. 6f) to thewinding 44 of FIG. 6a. A flux flow is established in the legs 49, 50 and51 in the clockwise sense about the aperture 42. The points L7, K-7 andL-7 represent the states of saturation at remanence of these legs ontheir respective hysteresis loops of FIGS. 6]), 6c and 6d. After asequence of positive and negative current pulses applied to the winding43 (FIG. 6a), these last-mentioned states may be assumed by these legsin a different manner. An intense, negative excitation current pulse maybe applied to the winding 43. The legs 49, 50 and 51 are then in thestates of saturation at remanence represented by the points 1-6, K-6 andL 6 of the respective hysteresis loops of FIGS. 6b, 6c and 6d. Now, byapplying an intense, positive excitation current to the winding 43, thelegs 49, 50 and 51 are caused to assume the states of saturationrepresented, respectively, by the points J-7, K-7 and L-7. Thus, thestates of saturation of the legs 49, 50 and 51 represented,respectively, by the points J7, K-7 and L-7 are reached either from thestates of saturation represented by the points 1-5, K-5, L-S, or fromthe states represented by the points J-6,

21 K-6 and L-6. In either event, the transfluxor of FIG; 6a is in asignal-blocking condition.

Assume, now, that the current waveform 63 of FIG. 66 is applied to thewinding 43. The intense, positive current pulse 63a does not produce anysubstantial change of flux because a saturating flux in the clockwisesense with reference to the aperture 41 is established already in thelegs 49 and 51. Therefore, no matter how intense the positive excitationcurrent applied to the winding 43 may be, substantially no outputvoltage is induced in the output winding 54. However, the intensity ofthe subsequent negative excitation current pulse 63b (FIG. 6e) producesa magnetizing force tending to cause a counter-clockwise flux flowaround the flux path 57. However, such a flux flow is not establishedbecause the legs 49 and 50 are saturated at remanence in opposite sensesof flux flow with reference to the aperture 41. The law of continuity offlux flow would be violated, as discussed above in connection with FIG.1c, if a saturating flux flow were established by the negativeexcitation current pulse. Actually, small, minor hysteresis loops aredescribed by the points instantaneously representing the magnetic statesof the legs 49 and 51 which finally reach the states represented by thepoints J9 and L-9 on the hysteresis loops of FIGS. 6b and 6c. The minorhysteresis loops occur because the material has imperfectly rectangularsaturation characteristics. A repetition of the application of thesequence of the excitation pulses 63a and 63b shown in FIG. 6e to thewinding 43 (FIG. 6a) does not produce any reversals of flux previouslyestablished in leg 49. Therefore, substantially no output voltage isinduced in the output winding 54.

The operation of the two--aperture transfluxor in response to thesequence of the asymmetric excitation current pulses depends upon theratio between the length of the flux path 56 to the length of the fluxpath 57. The larger this ratio is, within reasonable limits, the lesscritical is the amplitude of the smaller pulse 63b, FIG. 60.Furthermore, the frequency of the output pulses may be made greaterbecause a pulse 63b, of greater amplitude than just suificient toreverse the flux in the shorter path 57, FIG. 6a, may be applied,whereupon the flux reverses more quickly than with a pulse 630 ofsmaller amplitude.

OTHER FORMS OF TRANSFLUXORS The two-aperture transfluxor of FIG. 7 isfabricated in the form of a disk 65 of magnetic material having a largeaperture 68 and a small aperture 69. A relatively long flux path 66encompasses both apertures, and a relatively short flux path 67encompasses only the smaller aperture 69; The ratio of the length of thelonger flux path 66 to that of the shorter flux path 67 is large (forexample, 4:1). Typical dimensions, in inches, of the two-aperturetransfluxor are shown in FIG. 7. The thickness of the disk 65 may be ofthe order of 0.100 inch. The positive and negative setting pulses aresupplied by a pulse source 70 to a winding 71 which links the magneticmaterial limiting the aperture 68. Pairs of preferably asymmetric,positive and negative current pulses are supplied by an A.C. source 72to a winding 73 which links the material limiting the aperture 69. Thepositive directions of current flow in the windings of FIG. 7 areindicated by arrows adjacent these windings. An output winding 74 linksa leg '76 of the transfluxor between the aperture 69 and the outerperiphery of the disk 65. The winding 74 is connected across a loadwhich may be, for example, an electrically-responsive light source, suchas a lamp 75. Illustratively, for a transfluxor having the abovedimensions, and operating in the Mode II described above, the negativesetting pulse from the pulse source 70 may be of the order of twoampere-turns, and the positive setting pulse may be of the order of twoampere turns. An average output load drawing about 0.2 watt can bedriven by 22 pairs of current pulses from the A.C. source 72 withpositive phase of an amplitude of the order of 1 ampere-turn andnegative phase of the order of 0.3 ampere-turn when the transfiuxor isin its signal-passing condition.

Note that a setting excitation current pulse does, in general, produce apulse in the output winding 74 due to the change of flux in the leg 76.Also, in the Mode II type of operation, as described above, the firstpositive excitation pulse applied to the power winding 73 causes avoltage to be induced in the pulse source winding 71 due to the changeof flux in the leg 78. However, if the magnetic circuit using atwo-aperture transfluxor is used to control a long sequence of pulsesapplied to the winding 73, then the feedback power from the power source72 to the pulse source 70 is relatively low because subsequentexcitation pulses applied to the power input winding 73 do not reactinto the control circuit, that is, the pulse source 70. The power gainresults from frequent changes of flux in the leg linked by the outputwinding. The flux changes are controlled by pulses in the input circuitwhich may occur infrequently.

A transfluxor may be considered as a magnetic device which provides alarge power or energy gain. In response to a control pulse having a verysmall energy level, the transfluxor is set so that it does, or does not,pass the A.C. power input signal to provide an A.C. output signal. Ifthe transfluxor is set to provide an output signal, then the energyinduced in the output winding is that derived from any desired number offlux changes in the leg linked by the output winding. If, on the otherhand, the transfluxor is set to provide no output signal, substantiallyno output signal results regardless of the number of cycles of power.input. The output signal is, in one sense, a carrier wave modulated tobe at full or zero amplitude depending on the last previous settingsignal. A further power gain results from the fact that the control andcontrolled circuits are substanially decoupled. Therefore, thecharacte-ristic of the load is relatively unimportant insofar as thecontrol signal is concerned.

A plurality of transfiuxors may be coupled together in order to obtainincreased power output. In such a case, the control, the power supply,and the output windings may couple all of the transfluxors. Also, toobtain better discrimination between the blocked and unblockedconditions, the transfluxors may be connected in tandem by coupling thecon-trolling winding through all the transfluxors, the power supply tothe first, the output of the first to the supply of the second, etcetera.

Another form of transfluxor may be polarity sensitive. Referring to FIG.8a, a polarity-sensitive t-ransfluxor is provided having at least fivedifferent apertures 81 through 85, inclusive. The diameters of theapertures are so chosen that there are approximately equal amounts ofmagnetic material in each of the legs located between adjacentapertures. This multi-apert-ure transfluxor has a relatively uniformthickness t as shown in the end view of FIG. 8b.

An input winding 86 links the magnetic material limiting the apertures82 and 84 by threading the winding 86 down through the aperture 82, then[from behind the transfluxor plate up around an edge thereof, over thetop surface, as shown, and then down through the aperture 84, andreturned to an A.C. power source 87 to which it is connected. Theapertures 82 and 84 are termed the reading apertures. Aperture 83 istermed a writing aperture. A write winding 88, which is connected to asignal source 89, links the magnetic material limiting the writingaperture 83. Apertures 81 and are termed dummy apertures. A dummywinding 90, which is connected to a DO source 91, links the magneticmaterial limiting the dummy apertures 81 and 85 by passing down throughthe aperture 81, then behind the transfiuxor plate to the aperture 85,then up through the aperture 85 and back to the DC. source 91. A switch118 is interposed in the dummy winding 90. An output winding 92 links aportion of the magnetic material individual to the reading aperture 84.A different output winding 93 links a portion of the magnetic materialindividual to the reading aperture 82.

The operation of the magnetic system of FIG. 8a 15 as follows:

Assume that the switch 118 is closed and then opened to apply a positiveexcitation current pulse to the winding 98. As before, arrows adjacentthe windings indicate the positive direction of current flow. This pulseestablishes a saturating flux around the dummy aperture 81 in aclockwise sense and saturating flux around the dummy aperture 85 in thecounter-clockwise sense. The sense of the saturating flux flow isindicated by the arrows adjacent the dummy apertures 81 and 85. Thesense of the saturating flux about the two dummy apertures 81 and 85 isdifferent because the winding 90 passes through dummy aperture 81 in adownward direction (as viewed in the drawing) and through the dummyaperture 85 in an upward direction. The setting of the legs limiting thedummy apertures may be a fabrication step, the legs being set once andfor all, and the winding 90 may now be removed.

Assume, now, that a positive excitation current pulse 1s applied to thewrite winding 88 by signal source 89. The intensity of the positiveexcitation current is made sufficient to establish a clockwise flux flowaround the aperture 83 only. 'The clockwise saturating flux is indicatedby the sol-id arrows adjacent the aperture 83. Consider the effect of atrain of one or more pairs of postive and negative excitation currentpulses which is applied to the winding 86 by the A.C. source 87. Theexcitation pulses of the train tend to establish a substantial flux flowabout each of the reading apertures 82 and 84. Because of the fluxconfiguration previously established, however, only the flux about thereading aperture 82 is reversed. This results from the fact that theflux previously established about the aperture 82 was in acounter-clockwise sense. The flux previously established about theaperture 84, on the other hand, was and remains in opposite senses withreference to the aperture 84 in the legs adjacent thereto. Therefore,voltages are induced in the output winding 93, but not in the outputwinding 92, by these reversals.

Consider, now, the effect of a negative excitation current pulse appliedto the write winding 88 by the signal source 89. The previouslyestablished clockwise saturating flux about the aperture 83 is reversed,and a counterclockwise saturating flux is established with reference tothe aperture 83. The sense of the counter-clockwise saturating fluxaround the aperture 83 is shown by the dotted arrows adjacent thereto.

In the case of the negative excitation write current, the sense ofsaturating flux flow around the aperture 84 is clockwise in both itsadjacent legs. However, the saturating fluxes established in the legsadjacent to the aperture 82 are now in senses opposite to each otherwith reference to the aperture 82. Consequently, when the train of pairsof positive and negative excitation pulses is applied to the winding 86,only the flux flow around the aperture 84 reverses. Therefore, outputvoltages are induced only in the output winding 92. The flux flow aboutthe aperture which responds to the train of positive and negative pulsesis always returned to its initial sense and, therefore, the read-out isnon-destructive. For example, the initial clockwise flux flow around theaperture 84 is reversed by the negative excitation pulse of the winding86, and the following positive excitation current reverses thesaturating flux back to the clockwise sense.

The multi-aperture transfluxor can also be arranged to furnish apositive-negative or negative-positive pulse combination on an outputwinding in accordance with the polarity of the write excitation currentpulse. Referring to FIG. 80, there is shown a magnetic system similar tothat of FIG. 8a with the exception that a single read winding 96 isprovided in lieu of the read windings 92 and 93 of FIG. 8a. The readwinding 96 is threaded down through the aperture 81, then up through theaperture 82, then in front of the transfluxor plate to and down throughthe aperture 84, then up through the aperture 85, and returned to theoutput. A saturating flux flow is established about the dummy aperturesas described in connection with FIG. 8a.

In operation, the positive or negative write pulse is applied to thewrite winding 88 by the signal source 89. The pairs of excitation pulsesare applied to the reading apertures 82 and 84 by means of the powerinput winding 86, as before. If a positive excitation current pulse isapplied to the write winding 88 by the signal source 89, a clockwisesaturating flux is established around the writing aperture 83, as shownby the solid arrows adjacent thereto. Thus, only the flux in the legswhich limit the reading aperture 82 can reverse direction when a pair ofpulses is applied to the winding 86. The first positive excitationcurrent pulse in the winding 86 establishes a clockwise saturating fluxflow about the aperture 82, and the following negative excitationcurrent pulse changes the sense of the saturating flux flow to itsinitial, counterclockwise sense. The output pulse combination induced inthe output winding 96 is illustrated at 97 to be a voltage pulse of onepolarity, taken as positive, followed by a pulse of the oppositepolarity.

Conversely, when a negative excitation current pulse is applied by thesignal source 89 to the write winding 88, a saturating flux flow in thecounter-clockwise sense with respect to the aperture 83 is established,as illustrated by the dotted arrows. Thus, only the legs limiting theaperture 84 respond to the pairs of excitation pulses applied to thewinding 86. The first negative excitation pulse in the winding 86 fromthe A.C. source 87 establishes a counter-clockwise flux flow about theaperture 84, and the next succeeding positive excitation current pulsechanges the flux flow around the aperture 84 back to its initialclockwise sense. A diiferent output pulse combination 98 consisting of anegative pulse followed by a positive pulse is thus induced in theoutput winding 96. Note, however, that if the first excitation pulse inthe winding 86 is positive for that first positive pulse, only the fluxflow around the aperture 84 remains substantially unchanged.

Furthermore, the manner of threading the output winding 96 through theapertures 82 and 84 aids in elimination of the noise voltage in theoutput signal. Again, noise represents a signal which exists because ofthe imperfect rectangularity of the hysteresis characteristics of thematerial. Thus, for example, consider the effect on the leg locatedbetween the reading aperture 84 and the dummy aperture of a positiveexcitation pulse applied to the write winding 88. The specified legbecomes slightly more saturated in the clockwise sense because of theimperfect rectangularity of the hysteresis loops of the material and thechange of flux in this leg induces a noise voltage opposite to theread-out voltage in the output winding 96. However, the effect of thisnoise signal is to reduce the amplitude of the output signal induced inthe output winding 96 resulting from the large flux change aroundaperture 82. Consequently, the noise signal is thus overridden by themuch larger desired output signal. The noise signal resulting from thenegative excitation pulse applied to the winding 88 is similarlyoverridden by the desired output signal.

Note that the manually-operated pulse sources, such as the circuitcomprising the battery 110, switches 111 and 112, and resistor 121 ofFIG. lb, or the like circuit of FIG. 6a, may be employed as the pulsesource 47 of FIG. 5a. Further, suitable electronic pulse sources, forexample, employing vacuum tubes, may be employed for any of the pulsesources or any of the A.C. sources shown herein.

Also note that the transflnxor has two conditions characterized hereinrespectively as signal-blocking and signal-transmitting. However, theroles of these conditions may be interchanged, for example, by insertingthe A.C. source 72 in series with the load, the lamp 75, in thearrangement of FIG. 7. In this case, the condition of the transfluxorformerly denominated signal-blocking actually causes a signal to bepassed, because the source 72 has in series a comparativelylow-impedance winding, the current in which causes substantially no fluxchange in the transfluxor. Conversely, the signal-transmitting conditionof the transfluxor now causes the series source to be substantiallyblocked, because the source is in series with a comparativelyhigh-impedance winding which changes flux substantially, therebyself-inducing a comparatively large back SUMMARY From the foregoing, itis clear that the various transfluxors of the present invention hereindescribed are inexpensive, easily constructed, magnetic devices whichcan perform a variety of useful functions advantageously. Examples areas follows:

(a) As a control device, a transfluxor can control the transmission ofan alternating signal which is applied to the excitation winding linkedto the magnetic material limiting the aperture around which the selectedflux path is taken. When a transfiuxor is set to a signal-blockingcondition, the alternating input signal is not transmitted. When thetransfiuxor is set to a signal-transmitting condition, the alternatinginput signal is transmitted. By suitably selecting the number of turns,step-up or stepdown ratios are obtainable.

(b) As a one-bit storage register, the trans-fluxor is also very useful.In information-handling and computing sys tems a wide use is made of onebit storage registers. A common example of such a register is aflip-flop circuit. Although magnetic toroids have also been used forthis purpose, they have the disadvantage that a feedback or rewritecircuit must be associated therewith because the read-out isdestructive. Furthermore, the reading and writing circuits of thetoroids are tightly coupled by virtue of the fact that they are commonlylinked to the same toroid.

The transfluxor devices overcome these disadvantages. By applying ahigh-frequency alternating signal to a transfluxor, a continuous, visualor other suitable indication of the stored information can be obtained.A typical example of the use of a transfiuxor as a one-bit storageregister is illustrated in FIG. 7 of the drawing. The state of storageof the device may be displayed by the indicating lamp 75 whenradio-frequency current is applied to the winding 73. The lamp 75 may beof an incandescent type in order conveniently to match the low impedanceof the lamp to the low impedance of the single-turn linkage of themagnetic circuit.

As a command-storing gate, the transfluxor has another useful function.Here, it may be used as a gate for the interrogating pulses which aregated for either blocking or passage in response to a writing or controlsignal, the gate obeying the last command continuously.

A two-aperture command storing gate may be that shown in FIG. 6a or FIG.7, for example. The circuit used to set the transfluxor may also be of amulti-coincident type wherein the simultaneous presence of two or moresetting signals is required to set the transfluxor. Thus, in themodification of FIG. 7, for example, the winding 71 may be supplied withtwo discrete sets of current pulses which must be coincident in order toprovide sufiicient magnetizing force to establish a flux flow in thelonger path 66 which encompasses both apertures 68 and 69. A differentwinding, such as the winding 71, may be employed for each set of currentpulses, if desired. Two different modes of operating the two-aperturetransfluxor have been described. The mode of operating the two-aperturetransfiuxor of FIG. a employs symmetrical reading pulses. The mode ofoperating the transfluxor of FIG. 6a employs asymmetrical readingpulses. The two-aperture transfluxor of FIG. 7, however, is for somepurposes preferred over the two-aperture transfiuxor of FIG. 5a.

A magnetic system using a three-aperture transfluxor as a commandstoring gate is shown in FIG. lb. Various arrangements to obtainimproved signal-to-noise ratios for the three-aperture gate or storageregister are shown in FIGS. 4a, 4b, and 40.

(d) The transfiuxor device is also useful as a polaritysensitivecircuit. That is, in response to a positive pulse applied to an inputwinding, an output signal can be furnished on an output winding inaccordance with the condition of the transfiuxor in response to aprevious control or writing circuit. FIGS. 8a and 8c illustrate examplesof this type of polarity-sensitive circuit.

From the foregoing, it is apparent that the transfluxor affords a greatmany different advantageous uses for the control of energy or for thestorage of signals.

What is claimed is:

1. A magnetic system comprising a magnetizable medium having thecharacteristic of being substantially saturated at remanence, saidmedium having a plurality of aligned apertures providing a plurality ofadjacent flux paths within said medium, one of said paths being betweenat least two others of said paths and having first and second portionsin common, respectively, with said two other paths, means forestablishing along one of the said two other flux paths a saturatingflux in a first of said portions in a first sense with respect to saidone path, and means for establishing along the other of said two otherflux paths saturating flux in said second portion selectively either insaid first sense or in the opposite sense with respect to said one path.

2. A magnetic system comprising a body of magnetic material capable ofbeing saturated at remanence by saturating flux flow in one or the otherof two different senses, said body having three aligned aperturesproviding at least three adjacent flux paths within said medium, anintermediate one of said flux paths including two different portions,one of said portions being in common with a part of one of said adjacentflux paths, the other of said portions being in common with a part ofanother of said adjacent flux paths, and means for establishing saidcommon portions selectively either in the same or in opposite states ofsaturation at remanence with reference to said intermediate flux path.

3. A device comprising a body of magnetic material having thecharacteristic of being substantially saturated at remanence, said bodyhaving at least three apertures and three windings linking respectivelythe material limiting said apertures, means for applying separateelectrical impulses respectively to the windings linking the magneticmaterial limiting two of said apertures, and means for applying analternating electrical signal to the third of said windings.

4. A device as recited in claim 3 including an output winding linking aportion of the magnetic material limiting said third aperture.

5. A device as recited in claim 3 wherein said two electrical impulsesare successively applied by said first named means to said windings.

6. A device as recited in claim 3 wherein said two electrical impulsesare simultaneously applied by said first named means to said windings.

7. A device as recited in claim 3 wherein the dimensions of saidapertures are substantially equal.

8. A device as claimed in claim 3 wherein said body has flux paths, oneindividually around each of said apertures, the smallest cross-sectionaldimensions of magnetic material in each of said flux paths beingsubstantially equal.

9. A device as claimed in claim 3 and further including an outputwinding, said body having flux paths one individually around each ofsaid apertures, each of two portions of one of said flux paths being incommon with a 27 portion of a difierent one of the other of said paths,said output winding linking the magnetic material in a portion of saidone flux path other than said two common portions.

10. A magnetic device as claimed in claim 3 and further including anoutput winding, said body having individual flux paths in said materialone about each of said apertures, each of two portions of one of saidflux paths being in common with a portion of a difierent one of theother of said paths, said output winding linking the magnetic materialin one of said two common portions of said one flux path.

11. A magnetic device as claimed in claim 3 and further including anoutput winding, said body having individual flux paths in said materialone about each of said apertures, each of two portions of a first ofsaid flux paths being in common with a portion of a different one of theother of said paths, said output winding linking the magnetic materialin the flux path around a second of said apertures which is common tothe flux paths around said References Cited in the file of this patentUNITED STATES PATENTS 2,682,632 Cohen June 29, 1954 2,818,555 Lo Dec.31, 1957 2,818,556 L0 Dec. 31, 1957 2,842,755 Lamy July 8, 19582,869,112 Hunter Jan. 13, 1959 2,902,676 Brown Sept. 1, 1959 OTHERREFERENCES The Transductor Amplifier, by Ulrik Krable, 1947, pp. 1-176(FIGS. 3, 4 and pp. 2627 relied on).

